This patch allows you to interact with any player horde or alliance as if they were your own faction. Only while in a group or a raid. This means trades, grouping, healing, enchanting in trade window and rez's work. I attempted to change the code so you could turn it on and off based on the mangosd.conf twoside options but for some reason I'm stuck. Anyway, here's the completed patch without conf checks. This patch was originated by False.Genesis. The ability to trade was possible due to help from Prefect, one of my server admin. Onwards to the patch. It is a git patch and my server version is 7464.
Patch posted below.
[uPDATE - NEW PATCH JUNE 9 2010 - WORKING MaNGOS/0.16.0 (* * Revision 10044 - *) ]